Answer: 2n² − n.
- A 2n
- B n²
- C 2n² − n
- D 2n²
Correct answer: C. 2n² − n
Explanation: The n diagonal pairs are forced to be present; the remaining n² − n off-diagonal pairs are free, giving 2n² − n.
Concept context
Types of relations, equivalence classes, one-one and onto functions, composition, and invertible functions